Too soon really. I mean before the sun set on the British Empire they will shine the brightest. Also depending on OTL WW1 they might keep their power. In the 19th century we are on the current TL the British are the undisputed master of seas, so we have a long way till the British fall.Basically the British empire's sun sets while the American's becomes brighter. America basically played the role of the premier naval power and has the same geopolitical concerns as Britain, so basically the Greeks will ally themselves to the Britain-American alliance.
Greece can't ally itself with the premier land power because Greece works due to its ocean. Nothing can change that.